1. Field of the Invention
The present invention relates to the field of article stacking devices, and more particularly to stacking devices for assembling a stream of printed products into stacks or bundles and ejecting the stacks of printed products. Specifically, the present invention relates to devices intended to reduce the prospects for inadvertent interference with the stacking mechanism or to reduce the potential for injury.
2. Discussion of the Art
Newspapers and other printed matter fed from a printing press or inserting machine are generally folded or delivered in a continuous stream with the papers oriented in an overlapped or imbricated relationship. The stream of papers are received and stacked by the stacking apparatus or stacker which must operate at high speeds. The stacker orients the papers in the stacks and ejects the bundles of papers in at least two directions at a rate which exceeds one stack ejected per second.
Stackers generally operate by moving a fork into the continuous stream of papers to collect a desired number of papers which form a portion of the bundle. Forks are generally spring-mounted to a chain drive which rotates to continually receive and deliver batches of papers to a bucket or stacking section of the stacker. After a predetermined count of papers are received on a fork, a next fork intercepts the paper stream and begins collecting papers for the next batch. The forks move downward as the papers are collected and drop the completed batches onto a turntable which collects the papers in a stack.
Since newspapers and other printed materials generally have a thickness which is greater along the folded side of the paper than on the unfolded side of the paper, two or more batches are generally stacked on the turntable with the folded edges of the successive batches rotated 180xc2x0 to form a bundle. This provides a more even stacking of the papers. In order to form the bundle with the alternately rotated batches, the stacking platform or turntable is driven by a heavy-duty motor which rotates the turntable 180xc2x0 between receiving successive batches from the forks.
Once a predetermined bundle size is reached, the bundle is ejected from the stacker by, for example, pushing the bundle off the turntable with a pusher bar. Thus, the bucket area or stacking region where the bundles are formed on the turntable is a complex mechanical region where a number of moving components are operating very rapidly to keep up with the demands of the printing press. For example, printed products are dropped from overhead. The turntable undergoes periodic rotation. The bundle eject mechanism is periodically operated to remove the bundle from the turntable. Accordingly, this region has been maintained at least partially open to allow access to the various components and provide ease of maintenance access. However, in an effort to preclude interference with this complex mechanical operation, and also to reduce the possibility for potential injury, improvements to the stacker are desired.